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Cutting performance of advanced multilayer coated (TiAlN/ AlCrN) in machining of AISI D2 hardened steel

Jasni, Nur Akmal Hakim and Lajis, Mohd Amri (2013) Cutting performance of advanced multilayer coated (TiAlN/ AlCrN) in machining of AISI D2 hardened steel. Other thesis, Universiti Tun Hussein Onn Malaysia.

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Abstract

The hard machining of hardened steeI with advanced cutting tool has several advantages over conventional method such as short cycle time, process flexibility, compatible surface roughness, higher material removal rate and less environment p-oblems with absence of cutting fluid. However, caused severe tool wear and changes to quality and pehrmance of product due to higher mechanical stress and heat generation. Thus, proper criteria should be adopted to keep the longer tool life and maintaining the quality of suface integrity. In this work, an experimental investigation was conducted to characterize the machinability of multilayer TiAlNIAlCrN coated carbide tools and surface integrity in end milling of AISI D2 hardened steel (58-62 HRC) on a Vertical Machining Centre (VMC). The cutting variables were cutting speed (80-120 dmin) and radial depth of cut (3-5 rnrn), meanwhile feed per tooth (0.05 mm) and depth of cut (0.5 mm) were kept constant. Tool life and volume of material removed decreased as cutting speed and radial depth of cut increased due to higher temperature and contact area. Built-up edge formation, groove formation, and edge chipping were the dominant tool faiIure modes; however, the cutting tool was subjected to adhesion and abrasive wear for the duration of testing. The highest volume of material removed and tool life were 1500 mm3 and 4.97 min which associate to cutting speed of 100 dmin and radial depth of cut of 4 mm. The surface roughness, Ra values attained throughout the experiments were in range of 0.20 to 0.45 p which may acceptable in mould and die fabrication. The optical microscope observations show that the milled surface is anisotropic in nature. Meanwhile, the surface defects observed during machining included feed marks, grooves, microchips or debris and cavities and the existence of surface defects caused by thermal softening of the material and interaction between cutting tool and workpiece. This study showed that a thin layer of plastic deformation was formed in the immediate sub-surface of the workpiece, and the microhardness was altered to a depth of 0.28 mrn beneath the machined surface due to high pressure and elevated heat. Nevertheless, all cutting tools experienced excessive coating delamination by crack and strip fiom the substrate due to high fiiction and thermal cycling generated and low toughness of the coating. It can be concluded that hard machining can be carried out for AlSI D2 hardened steel with mdtilayer TW/AlCrN coated carbide tooling because the process has been proven to produce high productivity and functional performance of quality machined parts with respect to surface integrity.

Item Type: Thesis (Other)
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ1125-1345 Machine shops and machine shop practice
Depositing User: Normajihan Abd. Rahman
Date Deposited: 18 May 2015 07:17
Last Modified: 18 May 2015 07:17
URI: http://eprints.uthm.edu.my/id/eprint/6872
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